In the following models of 1,3-diene conformers, the sp² carbon atoms are dark gray and the hydrogens are cyan. The different phases of the molecular orbitals are colored red and blue and are separated by nodal surfaces at which electron density is zero. Orbital amplitude and transparency may be changed by clicking appropriate buttons under the display.
π-orbitals are formed by overlap of p-orbitals having like phases. The lowest energy π-orbital, π₁, has a single nodal plane, that of the coplanar atoms of the diene. Higher energy π-orbitals may be viewed by clicking buttons under the display. An increasing number of nodes parallels the increase in energy. The two lowest energy π-orbitals are bonding. The two higher energy orbitals are antibonding. The HOMO is π₂; the LUMO is π₃*.
The models can be rotated by clicking on the structure and dragging the mouse. Holding the shift key during this operation allows zooming.